agree the terms

Isn’t “agree the terms” simply bad form? The following is taken from today’s online Guardian in a quote from Theresa May: . . . the prime minister said she believed it was “necessary to agree the terms of our future partnership alongside those of our withdrawal from the European Union”. Then as the article continues, the same usage appears in the Guardian’s own words: “The EU institutions and 27 remaining member states, however, have long said they were determined the divorce settlement, such as the rights of EU citizens in the UK and Britons on the continent and the size of Britain’s exit bill, must first be agreed before substantive talks on a future relationship could begin.”

Agree to the terms, yes; but agree the terms?

Be agreed upon, yes; but settlement be agreed before?

I have not run across this usage in US English, so is it something happening in British writing/speech?

'Agree' can be used intransitively and transitively. According to Merriam Webster, your example is "chiefly British" - which I guess means it does come up but is rare in the US whereas it is standard in British English (and not "bad form" at all, please note that 'agree to the terms' changes the meaning, 'agree on or upon' is the only option here). Oxford dict:2.1 with object Reach agreement about (something) after negotiation.‘if they had agreed a price the deal would have gone through’no object ‘the commission agreed on a proposal to limit imports’https://en.oxforddictionaries.com/definition/agree